First of all I'd like to say thank you to everyone here.
I've been lurking for 2 years now and consider myself an armature chemist as a result.
This is my 3rd time opening a pool.
33' round (16.5 diameter)
Estimated 28,000 gallons
However it historically reacts like it is 35000 gallons.
That said, this year I started without a cover and had to rake and scrub.
I started with a 0 FC a few days ago with a half full pool and CYA at 15.
I've been keeping the FC around 10-15 to kill algae. Once it did drop to 2 overnight.
So I keep testing every 3 hours - backwashing every hour or so at this point. (5 lbs of DE on top of a sand filter)
Here is the oddity.
The last time I scrubbed my CYA test shot up to over 100.
I did add a 4 tab floater of 90% trichlor tabs to slowly raise my CYA but that shouldn't account for the high reading.
Is there something about sustained shocking that will cause false readings?
PH was at 7.2 when I started, it has been around 7.8 while shocking and that hasn't changed.
TA has stayed consistent at 100 throughout.
I'll keep up with the persistence and patience.